JP6871991B2 - Effervescent thermoplastic resin particles, thermoplastic pre-foamed particles, thermoplastic foam molded products and methods for producing them. - Google Patents

Description

The present invention relates to effervescent thermoplastic resin particles having excellent heat resistance.

As the foamable thermoplastic resin particles, foamable polystyrene resin particles are well known, and by using the foamable polystyrene resin particles, an in-mold foam molded product can be easily obtained at low cost. However, since the monomer constituting the polymer is styrene, the foamed molded product is used in applications where the temperature is relatively high, for example, a heat insulating material for piping, a heat insulating material for roofing, an automobile member, and a solar system. There is a drawback that it cannot be used for applications that require heat resistance due to insufficient dimensional stability when it is left in a high temperature for a long period of time, such as a heat insulating material. Further, in this field, higher heat resistance is required in recent years.

Regarding this problem, Patent Document 1 proposes a method for defining the ratio of alpha-methylstyrene to acrylonitrile and styrene as a method for improving heat resistance. However, in this method, since styrene is present in the monomer composition, the heat resistance performance is insufficient for the quality required by the market.

Further, Patent Documents 2 to 4 propose a method of copolymerizing alpha-methylstyrene with acrylonitrile, styrene, etc., and adjusting the average chord length, the amount of easily volatile foaming agent, and the amount of plasticizer in order to further improve the heat resistance performance. .. With this method, foaming can be performed up to 40 times, and a foamed molded product having good surface properties can be obtained. However, even in this method, the heat resistance performance is insufficient due to the influence of styrene in the monomer composition, and there is room for improvement.

Japanese Unexamined Patent Publication No. 2001-181433 JP-A-2007-191518 Japanese Unexamined Patent Publication No. 2007-2387771 JP-A-2007-246566

In view of the above circumstances, an object of the present invention is to provide foamable thermoplastic resin particles having improved heat resistance.

The present inventors have completed the present invention as a result of diligent research in order to obtain foamable thermoplastic resin particles having improved heat resistance for the purpose of improving the above-mentioned drawbacks of the prior art. ..

That is, the first of the present invention is an effervescent thermoplastic resin particle in which the monomer composition constituting the polymer is 60 to 80 parts by weight of alpha-methylstyrene and 40 to 20 parts by weight of acrylonitrile, and remains. Foamable thermoplastic resin particles having a monomer component content of 0.5% by weight or less.

The foamable thermoplastic resin particles according to the first invention, wherein the second invention is used at a foaming ratio of 2 to 15 times.

The first or second invention is characterized in that the average chord length of bubbles on the cut surface of a foamed molded article having a foaming ratio of 10 times obtained from the foamable thermoplastic resin particles is 20 μm or more and 60 μm or less. Effervescent thermoplastic resin particles according to the invention.

The fourth invention is characterized in that the dimensional change rate when the foamed molded product obtained from the foamable thermoplastic resin particles is treated at 90 ° C. for 24 hours is less than 0.15%. The foamable thermoplastic resin particles according to any one of the inventions of.

The foamable thermoplastic resin particles according to any one of the first to fourth inventions, characterized in that the surface layer of the foamable thermoplastic resin particles is coated with a mixture of a plasticizer and a pigment. ..

A sixth invention is a thermoplastic pre-foamed particle, which comprises foaming the foamable thermoplastic resin particles according to any one of the first to fifth inventions at a foaming ratio of 2 to 15 times.

A seventh invention is a thermoplastic foam molded product obtained by in-mold molding of the thermoplastic prefoamed particles according to the sixth invention.

From the present invention, foamable thermoplastic resin particles having improved heat resistance can be obtained.

The present invention is an effervescent thermoplastic resin particle composed of 60 to 80 parts by weight of alpha-methylstyrene and 40 to 20 parts by weight of acrylonitrile when the monomer composition constituting the polymer is 100 parts by weight. The amount of the remaining monomer component is 0.5% by weight or less.

The present invention is characterized in that it does not contain a third component such as styrene that lowers heat resistance, and the monomer component constituting the polymer is composed of alpha-methylstyrene and acrylonitrile. As shown in Cited Patent Document 4, when styrene is contained in the monomer composition constituting the polymer, the heat resistance is deteriorated.

The amount of alpha-methylstyrene used in the present invention is 60-80 parts by weight. If the amount used is less than 60 parts by weight, the heat resistance tends to decrease. If it exceeds 80 parts by weight, the polymerization conversion rate is lowered, and a large amount of monomers remains in the resin, so that the heat resistance is deteriorated. The amount of alpha-methylstyrene is preferably 63 parts by weight or more, more preferably 65 parts by weight or more. Further, 77 parts by weight or less is preferable, and 75 parts by weight or less is more preferable. By further adjusting the ratio of alpha-methylstyrene, the heat resistance during low-magnification foaming and the fusion property between resin particles can be further improved.

The amount of acrylonitrile used in the present invention is 20 to 40 parts by weight in order to improve the polymerization conversion rate of the composition. If the amount used is less than 20 parts by weight, the conversion rate of the composition decreases, and a large amount of monomer remains in the resin, resulting in deterioration of heat resistance. If it exceeds 40 parts by weight, the polymerization conversion rate does not change, the resin is colored yellowish brown, and the internal fusion tends to be further deteriorated. The amount of acrylonitrile is preferably 37 parts by weight or less, more preferably 35 parts by weight or less. Further, 23 parts by weight or more is preferable, and 25 parts by weight or more is more preferable.

The monomer component contained in the foamable thermoplastic resin particles of the present invention is less than 0.5% by weight. Preferably, it is 0.4% by weight or less. Good heat resistance can be obtained when the amount of the remaining monomer component is 0.5% by weight or less. The amount of the remaining monomer component means the total amount of the remaining unreacted material of the monomer composition constituting the foamable thermoplastic resin particles. Even if the monomer component is, for example, 0.1% by weight or more, particularly 0.2% by weight or more, it does not adversely affect the present invention.

The good heat resistance referred to in the present invention means that the rate of change in heating dimensions after 24 hours at 90 ° C. is less than ± 0.15%.

The foaming ratio of the present invention is preferably 2 to 15 times. A more preferable range is 5 to 10 times. The expansion ratio region in this range is characterized by a small rate of dimensional change over time and high mechanical strength. Due to this feature, it can be used for applications such as automobile members, heat insulating members / structural members of home appliances, and parts trays for robot lines.

In the foamable thermoplastic resin particles of the present invention, the average chord length of bubbles on the cut surface of the foamed molded product obtained from the foamable thermoplastic resin particles is preferably 15 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more. It is preferably 80 μm or less, more preferably 60 μm or less, and further preferably 50 μm or less.

If the average chord length is too short, the film thickness of the cells constituting the foam tends to be thin, and the surface properties and heat resistance tend to deteriorate. If the average string length is too long, heat resistance can be maintained, but surface properties and internal fusion tend to deteriorate.

The average chord length of bubbles on the cut surface of the foam can also be controlled by the amount of bubble adjusting agent (nucleating agent) used. For example, increasing the amount of the bubble adjusting agent (nucleating agent) reduces the average chord length, and decreasing the amount of the bubble adjusting agent (nucleating agent) increases the average chord length.

Examples of the bubble adjusting agent (nucleating agent) used in the present invention include methyl methacrylate-based copolymer, polyethylene wax, talc, fatty acid bisamide, ethylene-vinyl acetate copolymer resin, and the like. Specific examples of the fatty acid bisamide include methylene bisstearyl amide, ethylene bisstearyl amide, hexamethylene bispalmitate amide, ethylene bisoleic acid amide, and the like. Among these, fatty acid bisamide is preferable, and ethylene bisstearyl amide is more preferable because the average chord length can be easily adjusted.
The bubble adjusting agent (nucleating agent) is preferably 0.07 parts by weight or more, more preferably 0.1 parts by weight or more, and 0.3 parts by weight, based on 100 parts by weight of the monomer constituting the polymer. It is preferably parts or less, more preferably 0.2 parts by weight or less, still more preferably 0.15 parts by weight or less.

Examples of the effervescent agent used in the present invention include aliphatic hydrocarbons having 3 to 5 carbon atoms such as propane, butane and pentane, alicyclic hydrocarbons having 4 to 5 carbon atoms such as cyclobutane and cyclopentane, and methyl. Examples thereof include halogenated hydrocarbons such as chloride, dichlorodifluoromethane and dichlorotetrafluoroethane. These foaming agents may be used alone or in combination of two or more. Among these foaming agents, aliphatic hydrocarbons are preferable, and butane is preferable because it has good foaming power. More preferably, butane has an isobutane ratio of 50% by weight or less. When the isobutane ratio exceeds 50% by weight, the average chord length is less than 20 μm, the film thickness of the cells constituting the foam becomes thin, and the internal fusion, surface properties, and heat resistance tend to deteriorate.

Further, in the present invention, a foaming aid may be used in combination with the foaming agent. Examples of the foaming aid include solvents having a boiling point of 200 ° C. or lower under atmospheric pressure, and specifically, aromatic organic compounds such as styrene, toluene, ethylbenzene, and xylene, and cyclic compounds such as cyclohexane and methylcyclohexane. Examples thereof include aliphatic hydrocarbons, ethyl acetate and butyl acetate.
The foaming aid is preferably 1 part by weight or more, more preferably 5 parts by weight or more, further preferably 10 parts by weight or more, preferably 40 parts by weight or less, and more preferably 30 parts by weight, based on 100 parts by weight of the foaming agent. It is less than a part by weight, more preferably 25 parts by weight or less.

The content of the foaming agent in the foamable thermoplastic resin particles in the present invention is preferably less than 4% by weight, more preferably 3% by weight or less. When it is 4% by weight or more, the cycle at the time of molding tends to be long. The content of the foaming agent may be, for example, 1% by weight or more, particularly 2% by weight or more.

The weight average molecular weight Mw of the foamable thermoplastic resin particles in the present invention is preferably 80,000 or more and less than 120,000.

When the weight average molecular weight Mw of the foamable styrene resin particles is less than 80,000, the surface properties and heat resistance tend to deteriorate, and when the weight average molecular weight Mw is 120,000 or more, high heat resistance can be maintained but the foamability becomes low, and the surface surface. Sex tends to worsen.

The weight average molecular weight Mw can be controlled by the combination of the amount of the initiator used when polymerizing the thermoplastic resin particles and the polymerization temperature. For example, Mw can be lowered by increasing the amount of the initiator used and / or increasing the polymerization temperature.

Here, the weight average molecular weight Mw of the foamable thermoplastic resin particles in the present invention is a value measured under the conditions described later using a gel permeation chromatograph (hereinafter, may be abbreviated as “GPC”). Is.

Examples of the method for producing the foamable thermoplastic resin particles of the present invention include a method of impregnating particles obtained by a suspension polymerization method in an aqueous medium with a foaming agent, and pellets produced by bulk polymerization in an aqueous medium. It can be obtained by any method of impregnating with a foaming agent.

Among these, since spherical resin particles can be obtained and foamable thermoplastic resin particles can be obtained by consistently performing a polymerization step and a foaming agent impregnation step, suspension weight with good industrial productivity is also good. It is preferably manufactured legally.
That is, as a method for producing foamable thermoplastic resin particles, a styrene-based monomer and an acrylic acid ester-based monomer are added in the presence of a suspension agent, a polymerization initiator, and, if necessary, other additives. A method of starting the polymerization reaction and adding a foaming agent during suspension polymerization or impregnating the foaming agent after polymerization is preferable.

Examples of the suspending agent used in the suspension polymerization method in the present invention include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide and polyvinylpyrrolidone, and sparingly soluble inorganic substances such as calcium tertiary phosphate and magnesium bilophosphate. And so on. When a poorly soluble inorganic substance is used, the suspension stabilizing effect can be increased by using an anionic surfactant such as dodecylbenzenesulfonic acid sodium and α-olefin sulfonic acid sodium in combination. It is also effective to use a water-soluble polymer and a poorly soluble inorganic substance in combination.

As the polymerization initiator used in the suspension polymerization method of the present invention, a radical-generating polymerization initiator generally used for producing a thermoplastic polymer can be used. Typical polymerization initiators include, for example, azo compounds such as azobisisobutyronitrile, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, and lauroylperoxide-t-butyl. Peroxyisopropyl carbonate, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-amylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butyl) Peroxy) -3,3,5-trimethylcyclohexane, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexyl carbonate, di-t-butylperoxyhexahydroterephthalate and other peroxides Be done. These polymerization initiators may be used alone or in combination of two or more.

The amount of the polymerization initiator used in the suspension polymerization method of the present invention is preferably 0.01 parts by weight or more and less than 3 parts by weight with respect to 100 parts by weight of the total weight of the monomer. If the amount of the polymerization initiator used is less than 0.01 parts by weight, the polymerization rate tends to be slow, and conversely, if it exceeds 3 parts by weight, the polymerization reaction tends to be fast and control becomes difficult.

As an additive that can be added during suspension polymerization of the present invention, an external additive, a flame retardant, a flame retardant aid, etc. may be used as long as the effects of the present invention are not impaired.

As the flame retardant and the flame retardant aid used in the present invention, known and commonly used ones can be used. Specific examples of the flame retardant include halogenated aliphatic hydrocarbon compounds such as hexabromocyclododecane, tetrabromobutane, and hexabromocyclohexane, tetrabromobisphenol A, tetrabromobisphenol F, 2,4,6-tri. Brominated phenols such as bromophenol, tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A- Brominated phenol derivatives such as diglycidyl ether, 2,2-bis [4'(2 ", 3" -dibromoalkoxy) -3', 5'-dibromophenyl] -propane, brominated styrene-butadiene block copolymer , Brobroinated random styrene / butadiene copolymer, brominated butadiene / vinyl aromatic hydrocarbon copolymer such as brominated styrene / butadiene graph and copolymer (for example, EMERALD3000 manufactured by Chemtura, or Special Table 2009-516019 Disclosed in the Gazette). These flame retardants may be used alone or in combination of two or more.

As a specific example of the flame retardant aid, for example, an initiator such as cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane may be used. ..

As the external additive and the attachment used in the present invention, known and commonly used ones can be used, and pigments, plasticizers and the like are included.

Pigments used in the present invention include phthalocyanine-based pigments (phthalocyanine blue, phthalocyanine green, etc.), azo-based, condensed azo-based, anthracinone-based, perinone-perylene-based, indigo-thioindico-based, isoindoline non-based, and azomethine azo-based pigments. , Dioxazine-based, quinacridone-based, aniline black-based, triphenylmethane-based and other organic pigments.
When a pigment is used, the pigment is preferably 0.001 part by weight or more, more preferably 0.003 part by weight or more, and 0.1 part by weight with respect to 100 parts by weight of the monomer constituting the polymer. The following is preferable, and 0.07 parts by weight or less is more preferable.

When a plasticizer is used, the plasticizer used in the present invention includes phthalic acid-based ester compounds such as bis (2-ethylhexyl) phthalate and butyl benzyl phthalate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate and the like. Can be mentioned. In recent years, it is preferable to use diethylene glycol dibenzoate and dipropylene glycol dibenzoate (including a mixture thereof) from the viewpoint of environmental influence.
The plasticizer is preferably 0.001 part by weight or more, more preferably 0.005 part by weight or more, preferably 0.1 part by weight or less, and 0, based on 100 parts by weight of the monomer constituting the polymer. More preferably, it is 0.05 parts by weight or less.
The plasticizer is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, preferably 5 parts by weight or less, and more preferably 3 parts by weight or less with respect to 1 part by weight of the pigment. is there.

The surface layer of the foamable thermoplastic resin particles of the present invention is preferably coated with a mixture of a plasticizer and a pigment.

In the present invention, as a method of coating the surface of the foamable thermoplastic resin particles with the pigment and the plasticizer, a method of blending the foamable thermoplastic resin particles, the pigment and the plasticizer in a mixing device is preferable.

Examples of the mixing device used in the present invention include a super mixer, a nouter mixer, a universal mixer, a Henschel mixer, a radige mixer and the like. Among these, the super mixer is preferable because it has good stirring and mixing properties and can efficiently blend pigments and plasticizers.

Specific examples of external additives and accessories other than pigments and plasticizers include fatty acids such as triglyceride laurate, triglyceride stearate, and triglyceride linoleic acid, and fatty acids such as diglyceride laurate, diglyceride stearate, and diglyceride linoleic acid. Fatty acid monoglyceride such as diglyceride, monoglyceride laurate, monoglyceride stearate, monoglyceride linoleic acid, zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, zinc laurate, calcium laurate and other fatty acid metal salts, polyoxyethylene cetyl ether , Polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, nonionic surfactants such as polyoxyethylene oleate and the like. These external additives and attachments may be used alone or in combination of two or more. Further, these external additives and attachments may be added to the water system when impregnated with the foaming agent, or may be added and coated after dehydration or drying, regardless of the coating method. A preferred coating method is a method of coating by attaching after drying and mixing and stirring.

The foamable thermoplastic resin particles of the present invention are pre-foamed at a foaming magnification of 2 to 15 times to obtain thermoplastic pre-foamed particles. Then, it is heated and foamed to obtain a foamed molded product.

As the pre-foaming method, for example, a usual method such as heating with steam or the like to foam using a cylindrical pre-foaming device can be adopted.

As a method for foam-molding the pre-foamed particles, for example, a so-called in-mold foam-molding method, in which a pre-foamed particle is filled in a mold and a foamed molded product is obtained by blowing steam or the like to heat the mold, is common. The method can be adopted.

This application claims the benefit of priority under Japanese Patent Application No. 2014-198734 filed on September 29, 2014. The entire contents of the specification of Japanese Patent Application No. 2014-198734 filed on September 29, 2014 are incorporated herein by reference.

Examples and comparative examples are given below, but the present invention is not limited thereto.
The measurement and evaluation method was carried out as follows.

<Measurement of monomer component>
The monomer component in the obtained foamable thermoplastic resin particles is obtained by dissolving 1.0 g of foamable thermoplastic resin particles in 20 ml of dichloromethane, adding 0.005 g of an internal standard solution (cyclopentanol), and then gas. It was measured under the following conditions using chromatography (GC).
GC: GC-14B manufactured by Shimadzu Corporation
Column: PEG-20M 25%
Chromosorb W 60/80 (3.0m x 3.0mm ID)
Column temperature: 110 ° C
Detector (FID) temperature: 170 ° C.

<Molecular weight measurement>
For the obtained foamable thermoplastic resin particles, 0.02 g of the foamable thermoplastic resin particles are dissolved in 20 ml of tetrahydrofuran (hereinafter, may be abbreviated as "THF"), and then a gel permeation chromatograph. Using (GPC), GPC measurement was performed under the following conditions to obtain a GPC measurement chart and a weight average molecular weight (Mw) and a number average molecular weight (Mn). The obtained value is a relative value in terms of polystyrene.
Measuring device: High-speed GPC device HLC-8220 manufactured by Tosoh Corporation
Columns used: Tosoh, SuperHZM-H x 2, SuperH-RC x 2
Column temperature: 40 ° C., mobile phase: THF (tetrahydrofuran)
Flow rate: 0.35 ml / min, injection volume: 10 μL
Detector: RI.

<Preliminary foaming>
Effervescent thermoplastic resin particles were put into a pre-foaming machine with a stirrer and foamed by heating with steam to obtain pre-foamed particles having an apparent magnification of 10 times.

<Evaluation of moldability>
Using a molding machine [made by Daisen, KR-57], it is filled in a plate-shaped mold with a thickness of 20 mm and a size of 450 mm in length × 300 mm in width, and molded in the mold ^{with a blown steam pressure of 0.8 kgf / cm 2.} , A foam molded product was obtained. The surface condition of the molded product was visually observed and evaluated, and the following evaluation was carried out.

(1) Evaluation of fusion property The obtained thermoplastic resin foam was fractured, the fracture surface was observed, and the ratio at which the particles were fractured, not at the particle interface, was determined and fused according to the following criteria. The sex was judged.
⊚: The rate of particle breakage is 90% or more.
◯: The rate of particle breakage is 80% or more and less than 90%.
Δ: The rate of particle breakage is 70% or more and less than 80%.
X: The rate of particle breakage is less than 70%.

(2) Evaluation of surface properties The surface condition of the obtained thermoplastic resin foam was visually observed, and the surface properties were evaluated according to the following criteria.
◎: Very beautiful with no melting of the surface and no intergrains.
◯: The surface is melted and there are few intergrains, and it is beautiful.
Δ: The surface is melted and there are intergrains, and the appearance is slightly poor.
X: The surface is melted, there are many grains, and the appearance is poor.

(3) Measurement of average chord length of the cut surface of the foamed product The average cell diameter of the foamed product is averaged from the number of bubbles on a straight line (60 mm) of the foamed product by observing the cut surface of the foamed product with a microscope. The chord length was measured and used as the average cell diameter.
Average chord length t = line length / (number of bubbles x magnification of photo).

(4) Heat resistance evaluation A sample piece obtained by cutting a foamed molded product into a size of 150 × 150 × 20 (t) mm is subjected to JIS K6767 (dimensional stability at high temperature: method B) after 24 hours at 90 ° C. The rate of change in heating dimensions was measured.
⊚: The rate of change in heating dimensions is less than 0.10%.
◯: The heating dimensional change rate is 0.10% or more and less than 0.15%.
Δ: The heating dimensional change rate is 0.15% or more and less than 0.20%.
X: The heating dimensional change rate is less than 0.2%.

(Example 1) <Manufacturing of foamable thermoplastic resin particles>
In a 6 L autoclave attached to the stirrer, 108 parts by weight of pure water, 0.08 parts by weight of tricalcium phosphate, 0.006 parts by weight of α-olefin sulfonate, and di-t-butylperoxyhexahydro as an initiator. 0.773 parts by weight of terephthalate, 0.16 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane, and 0.12 parts by weight of ethylene bisstearyl amide were charged as a nucleating agent. Subsequently, 70 parts by weight of the alpha-methylstyrene monomer and 30 parts by weight of the acrylonitrile monomer were charged while stirring at 250 rpm, and then the temperature was raised to 98 ° C. Subsequently, the mixture was kept at 98 ° C. for 9 hours to obtain thermoplastic resin particles. Then, the temperature was raised to 114 ° C., and the temperature was maintained at 114 ° C. for 3 hours.

After cooling to 95 ° C., 0.5 part by weight of cyclohexane as a foaming aid and 2.52 parts by weight of butane as a foaming agent were press-fitted into the autoclave, and the temperature was raised to 110 ° C. again. Then, after keeping the temperature at 110 ° C. for 15 hours, the mixture was cooled to room temperature, and the polymer slurry was taken out from the autoclave. The removed polymer slurry was washed, dehydrated and dried to obtain effervescent thermoplastic resin particles.

<Manufacturing of preliminary foamed particles>
The obtained foamable thermoplastic resin particles were sieved to separate the foamable thermoplastic resin particles having a particle size of 0.6 mm to 1.4 mm.

1000 g of the separated effervescent styrene resin particles were pre-foamed at a bulk ratio of 10 times ^{using a normal pressure pre-foaming machine under the condition of blowing vapor pressure of 0.6 kgf / cm 2.} At this time, air was cut into the blown steam to adjust the blown steam temperature. Then, it was left at room temperature for one day to cure and dry.

<Manufacturing of in-mold foam molded product>
The obtained thermoplastic resin pre-foamed particles were filled into a plate-shaped mold having a thickness of 20 mm and a size of 450 mm in length and 300 mm in width using a molding machine [made by Daisen, KR-57], and the steam pressure was blown to 0. In-mold molding was performed at 8 kgf / cm ² to obtain a foam molded product.

Evaluation was performed using the obtained foamable thermoplastic resin particles and the foamed molded product, and the results are shown in Table 1.

(Example 2)
In <Production of Effervescent Thermoplastic Resin Particles>, the same as in Example 1 except that the monomer composition at the start of polymerization was changed to 78 parts by weight of an alpha-methylstyrene monomer and 22 parts by weight of an acrylonitrile monomer. By the operation, foamable thermoplastic resin particles, pre-foamed particles, and in-mold foamed molded product were obtained. The evaluation results are shown in Table 1.

(Example 3)
In <Production of Effervescent Thermoplastic Resin Particles>, the same as in Example 1 except that the monomer composition at the start of polymerization was changed to 62 parts by weight of an alpha-methylstyrene monomer and 38 parts by weight of an acrylonitrile monomer. By the operation, foamable thermoplastic resin particles, pre-foamed particles, and in-mold foamed molded product were obtained. The evaluation results are shown in Table 1.

(Example 4)
In <Production of foamable thermoplastic resin particles>, the foamable thermoplastic resin particles, pre-foamed particles, and in-mold foam molding were performed in the same manner as in Example 1 except that the holding time at 114 ° C. was changed to 2 hours. I got a body. The evaluation results are shown in Table 1.

(Example 5)
In <Production of foamable thermoplastic resin particles>, the foamable thermoplastic resin particles, pre-foamed particles, and in-mold foaming were carried out in the same manner as in Example 1 except that the ethylene bisstearyl amide was changed to 0.20 parts by weight. A molded product was obtained. The evaluation results are shown in Table 1.

(Example 6)
In <Production of foamable thermoplastic resin particles>, the foamable thermoplastic resin particles, pre-foamed particles, and in-mold foaming were carried out in the same manner as in Example 1 except that the ethylene bisstearyl amide was changed to 0.08 parts by weight. A molded product was obtained. The evaluation results are shown in Table 1.

(Example 7)
In <Production of Effervescent Thermoplastic Resin Particles>, after obtaining effervescent thermoplastic resin particles by the method described in Example 1, the effervescent thermoplastic resin particles are converted into the effervescent thermoplastic resin particles in a super mixer [Kawata, SMV-20]. A mixture of plasticizer: butylbenzyl phthalate: 0.01 part by weight and pigment: flotasianin blue: 0.005 weight by weight was added and blended for 60 seconds to obtain effervescent thermoplastic resin particles. Then, the pre-foamed particles and the in-mold foamed molded product were obtained by the same operation as in Example 1. The evaluation results are shown in Table 1.

(Example 8)
In <Production of Effervescent Thermoplastic Resin Particles>, after obtaining effervescent thermoplastic resin particles by the method described in Example 1, the effervescent thermoplastic resin particles are converted into the effervescent thermoplastic resin particles in a super mixer [Kawata, SMV-20]. Plasticizer: Mixture of 50-60% by weight of diethylene glycol dibenzoate and 40 to 50% by weight of dipropylene glycol dibenzoate (Product name JP120: J-Plus): 0.01 parts by weight and pigment: Flotasianin blue: 0.005 Effervescent thermoplastic resin particles were obtained by adding a heavy mixture and blending for 60 seconds. Then, the pre-foamed particles and the in-mold foamed molded product were obtained by the same operation as in Example 1. The evaluation results are shown in Table 1.

(Example 9)
In <Production of Effervescent Thermoplastic Resin Particles>, after obtaining effervescent thermoplastic resin particles by the method described in Example 1, the effervescent thermoplastic resin particles are converted into the effervescent thermoplastic resin particles in a super mixer [Kawata, SMV-20]. Plasticizer: Mixture of 50-60% by weight of diethylene glycol dibenzoate and 40 to 50% by weight of dipropylene glycol dibenzoate (Product name JP120: J-Plus): 0.01 parts by weight and pigment: Flotasianin blue: 0.05 Effervescent thermoplastic resin particles were obtained by adding a heavy mixture and blending for 60 seconds. Then, the pre-foamed particles and the in-mold foamed molded product were obtained by the same operation as in Example 1. The evaluation results are shown in Table 1.

(Example 10)
In <Production of Effervescent Thermoplastic Resin Particles>, after obtaining effervescent thermoplastic resin particles by the method described in Example 1, the effervescent thermoplastic resin particles are converted into the effervescent thermoplastic resin particles in a super mixer [Kawata, SMV-20]. Plasticizer: Mixture of 50-60% by weight of diethylene glycol dibenzoate and 40 to 50% by weight of dipropylene glycol dibenzoate (Product name JP120: J-Plus): 0.01 parts by weight and pigment: Flotasianin green: 0.05 Effervescent thermoplastic resin particles were obtained by adding a heavy mixture and blending for 60 seconds. Then, the pre-foamed particles and the in-mold foamed molded product were obtained by the same operation as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 1)
In <Production of Effervescent Thermoplastic Resin Particles>, the same as in Example 1 except that the monomer composition at the start of polymerization was changed to 85 parts by weight of an alpha-methylstyrene monomer and 15 parts by weight of an acrylonitrile monomer. By the operation, foamable thermoplastic resin particles, pre-foamed particles, and in-mold foamed molded product were obtained. The evaluation results are shown in Table 1.

(Comparative Example 2)
In <Production of Effervescent Thermoplastic Resin Particles>, the same as in Example 1 except that the monomer composition at the start of polymerization was changed to 55 parts by weight of the alpha-methylstyrene monomer and 45 parts by weight of the acrylonitrile monomer. By the operation, foamable thermoplastic resin particles, pre-foamed particles, and in-mold foamed molded product were obtained. The evaluation results are shown in Table 1.

(Comparative Example 3)
In <Production of Foamable Thermoplastic Resin Particles>, foamable thermoplastic resin particles were obtained by the method described in Example 1 of JP-A-2007-246566. Then, by the same operation as in Example 1, foamable thermoplastic resin particles, pre-foamed particles, and an in-mold foam molded product were obtained. The evaluation results are shown in Table 1.

Claims (11)

Foamable thermoplastic resin particles in which the monomer composition constituting the polymer is 60 to 80 parts by weight of alpha-methylstyrene and 40 to 20 parts by weight of acrylonitrile.
The nucleating agent to the polymer monomer 100 parts constituting the 0.07 parts by weight or more, unrealized 0.3 part by weight,
Effervescent thermoplastic resin particles, wherein the nucleating agent is polyethylene wax or fatty acid bisamide. The foamable thermoplastic resin particles according to claim 1, wherein the amount of the remaining monomer component is 0.5% by weight or less. The foamable thermoplastic resin particles according to claim 1 or 2, wherein the surface layer of the foamable thermoplastic resin particles is coated with a mixture of a plasticizer and a pigment. The thermoplastic pre-foamed particles according to any one of claims 1 to 3, wherein the foamable thermoplastic resin particles are foamed at a foaming ratio of 2 to 15 times. A thermoplastic foam molded product obtained by in-mold molding of the thermoplastic prefoamed particles according to claim 4. A method for producing effervescent thermoplastic resin particles, which comprises polymerizing a monomer composed of 60 to 80 parts by weight of alpha-methylstyrene and 40 to 20 parts by weight of acrylonitrile in the presence of a nucleating agent. ,
The amount of the nucleating agent is, relative to the monomer 100 parts by weight, 0.07 parts by weight or more state, and are less than 0.3 part by weight,
The manufacturing method nucleating agent is Ru Oh polyethylene wax or fatty acid bisamide. The production method according to claim 6, wherein the amount of the monomer component remaining in the foamable thermoplastic resin particles is 0.5% by weight or less. The production method according to claim 6 or 7, wherein a polymerization initiator is used at the time of the polymerization, and the polymerization initiator contains 1,1-bis (t-butylperoxy) cyclohexane. The production method according to any one of claims 6 to 8, further comprising a step of coating the surface layer of the foamable thermoplastic resin particles with a mixture of a plasticizer and a pigment. A method for producing thermoplastic pre-foamed particles, which comprises foaming the foamable thermoplastic resin particles obtained by the production method according to any one of claims 6 to 9 at a foaming ratio of 2 to 15 times. Method for producing a thermoplastic foamed molded thermoplastic pre-expanded particles obtained by the production method, characterized by mold forming form according to claim 10.